docs: def update_mapping_meta(self, doc_type, values, indices=None):
          """
          Update mapping meta
          :param doc_type: a doc type or a list of doctypes
          :param values: the dict of meta
          :param indices: a list of indices
          :return:
          """
          indices = self._validate_indices(indices)
          for index in indices:
              mapping = self.mappings.get_doctype(index, doc_type)
              if mapping is None:
                  continue
              meta = mapping.get_meta()
              meta.update(values)
              mapping = {doc_type: {"_meta": meta}}
              self.indices.put_mapping(doc_type=doc_type, mapping=mapping, indices=indices)